(a) Field of the Invention
The present invention relates to a photosensitive resin composition for color filter of liquid-crystal displays, and particularly provides a photosensitive resin composition for reducing aggregation of pigment, which has superior development properties, and forms images having no undercut after development in the formation of green pixels for color filter.
(b) Description of the Prior Art
Currently, the color filter is widely applied in LCDs (liquid-crystal displays), color fax machines, color cameras, etc. And the increasing demand for color LCDs in image equipment has brought about the development of more advanced technologies for manufacturing color filter.
The color filter can be manufactured by forming red, green and blue pixels on a transparent glass substrate using a dyeing method, printing method, electro-deposition method or pigment dispersion method. To increase contrast of the color filter, a black matrix is generally placed between the color pixels.
Regarding the aforementioned pigment dispersion method, the pigments are first dispersed in a photo-curable resin to produce a color photosensitive resin composition for forming a color resin layer of the pixels. Metal such as Cr or Cr2O3 or a black resin layer of the photosensitive resin is formed as a black matrix on a transparent (glass) substrate, then the photosensitive resin (color photoresist)dispersed with red pigment is coated onto the substrate. Red pixels are obtained after exposing through a photo mask and developing. The above procedures are repeated, i.e., coating, exposing and developing, to further obtain green and blue pixels.
In recent years, in addition to personal computers, LCDs are also applied in color televisions and monitors, particularly the large-sized color LCD TVs. For these applications, it is necessary to increase chroma and contrast.
Generally, the green pixels of color filter can be formed using a photosensitive resin composition adopting a halogenated phthalocyanine compound with central metal containing copper as the color pigment. However, the color pixels formed are unable to achieve the requirements for high contrast and high brightness. Hence, the Japanese Patent Publication No. 2003-161,828 disclosed adopting a halogenated phthalocyanine compound with central metal containing zinc in place of the copper.
However, when a photoinitiator, such as acetophenone disclosed in the Japanese Patent Publication No. 2009-222,752, or benzophenone disclosed in the Japanese Patent Publication No. 2009-198,751, is used in the photosensitive resin composition manufactured using the halogenated phthalocyanine compound with central metal containing zinc as a color pigment, then aggregation of pigment occurs, development properties are poor, and the problems of undercut occurs easily in the images formed after development.